Plug valve



March 23, 1943. R. BISCHOFF PLUG VALVE Filed Oct. 5, 1940 I 4 Sheets-Sheet 1 March 23, 1943. sa- 2,314,759

PLUG VALVE Filed Oct. 3, 1940 4 Sheets-Sheet 2 March 23, 1943. BISCHOFF'.

PLUG VALVE Filed Oct. 3, 1940 4 Sheets-Sheet 5 OPEN Pqsrrlcu v March 23, 1943. R. BISCHOFF PLUG VALVE Filed Oct. 3, 1940 4 Sheets-Sheet 4 w an Patented Mar. 23, 1943 UNITED STATES PATENT OFFICE PLUG VALVE 9 Robert Bischofl', Baltimore, Md. Application October 3, 1940, Serial N0. 359,464

8 Claims.

The invention relates to improvements in operating gear for rotary plug valves of the tapered or frustoconical type or other type of rotary valve in which it is helpful to move these valves in the direction of its axis, thus contributing to the facility with which the valve is operated in opening and closing. In the large sizes of valves the friction due to hydraulic pressure and other causes becomes so great that it offers almost insurmountable resistance to-opening the valve and one feature of 'the invention provides an automatic device for slightly raising or moving the valve in the direction of the axis prior to opening so as to lift the frustoconical valve member or plug from its corresponding frustoconical seat, the movement bez' ig slight, thereafter the operating force which has served to lift the plug isautomatically changed in its applica-' tion so that the valve is opened by the same operating force or tendency applied in the same direction without attention on the part of the operator or necessity for knowledge of the fact that opening is a two step operation consisting of first lifting and then turning in rotation through a limited arc.

Itis further of interest that the plug having been first lifted from its seat and then rotated to open position is in accordance with the functioning of the operating mechanism in its most complete and highly developed form again lowered to its seat in open position. This reseating of the plug prevents fouling of the contacting surfaces of the seat and plug and the accumulation of impurities thereon.

The lowering or reseating step is automatic as are the first two steps of the operation in that the motion of the control lever or other manual or power operating device is not varied for this purpose from the motion of" the operating lever of a simple plug valve which is not raised or lowered in opening or closing.

The valve operating device, in the form shown, comprises lifting means as a screw thread or the like on the valve stem and a follower or cooperating nut to which the operating force .is applied by means of a lever or equivalent means as aconnection from a power motor. ,In opening the valve the nut or corresponding element raises the plug. When the desired lifting effect has been accomplished, the nut becomes fixed relatively to the plug and stem and the operating force is apopenings in the open position of the valve and plied directly to the opening or turning of theplug on its axis. Atthe full open position the plug may be lowered'to its seat and in.clc'" ing the motion described is reversed and the plug is finally forced down on its seat by the action of the thread.

The features and details of the operating mechanism will be more fully described in connection with the drawings.

Throughout the discussion the valve axis is assumed tobe upright, the word raising being used to indicate a motion away from the seat in the direction of the valve or plug axis.

In operating large plug valves in controlling liquids under considerable pressure, it is noted that there. is, following the initial cracking of the valve in opening, an excess resistance to opening. This may be explained as due to the impingement of a jet of liquid thus released against the wallof the passage or opening in the plug, tending to rotate the same in the direction of closing. I

A further improvement forming part oi. the invention provides means for overcoming this resistance. This improved feature is embodied in a plug valve, the plug being hollow in that it has a central hollow extending in the direction of the axis and astationary core in said opening, the core being integral with the valve casing or affixed thereto for this purpose. The plug is thus inthe form of a frustoconicalsleeve rotatively mounted between the core and the frustoconical seat. The sleeve valve member has lateral openings to register with the usual seat the core has a passage aligned with the said seat openings so that the openings on that the sleeve valve member register with both the seat openings and the core passage in the open position of the valve.

By providing this stationary core withits passage permanently aligned with the seat opening any impact forces of a lateral jet or other forces resulting from the initial opening are taken up by the stationary core and transmitted to the casing without in any way interfering with the opening motion of the valve.

In the accompanying drawings, I have illustrated a valve embodying the features of my 'invention in the preferred form. r

In the drawings:

Fig. 1 is a top plan view of the valve casing with the operating mechanism exposed and in the relation corresponding to the closed position of the valve, the cover being removed.

Fig. 2 is a bottom plan view of the cover, portions being broken away for convenience of illustration.

Fig. 3 is an elevation of the casing which encloses the valve and the operating mechanism, the portion of the casing containing the latter being broken away and shown in section on the line 3-3 of Fig. 1.

Fig. 4 is a fragmentary view looking at the cam path and cam follower as from the left in Fig. 3, the view being in section on the lined-4 in Fig. 8, looking to the right.

Fig. 5 is a section on the line 5-5 in Fig. 8 looking downwardly and showing the carrier and its support or abutment and the cavities therein, the latter containing the carrier lugs which enter said cavities in the open position of the valve.

Fig. 6 is a vertical section on the line 6-6 in Fig. 3, taken in a plane at right angles to the plane of Fig. 3, the valve being closed.

Fig. 7 is a top plan view 01' the valve operating mechanism in the relation corresponding to the open position of the valve.

Fig. 8 isa section on the line 8-8 in Fig. '7.

Fig. 9 is a section corresponding to Fig. 6 showing the valve open and elevated, and is spaced in an axial direction from its seat in which position it is ready to-be lowered.

Fig. 10 is a central horizontal section through Referring to the drawings by numerals, each of which is used to indicate the same or similar parts in the different figures, the construction shown comprises a frustoconical plug or valve member I, having a valve stem 2, which is coaxial with the plug, extending upwardly above The valve casing 4 has a cover 4' secured by bolts and this casing is provided with upwardly extending struts B on which isrigidly supported the casing 1 for the valve. operating mechanism.

amodifled sleeve type of valve the same being shown in closed position.

Fig. 11 is a vertical axial section through the same on line lil I, Fig. 10, the valve being in closed position.

Fig. 12 is a similar section showing the valve open.

the axis of the valve in open position the same being taken in a plane at right angles to Fig. 12.

Fig. 14 is a perspective detail view of the core of the sleeve type valve.

In the operation of the valve, all motions are either rotative about the axis or motions of transition of the plug and stem in the direction of the axis, the valve being assumed for the purpose of description to be positioned with itsaxis vertical. The terms raising or lifting of the plug being used to, without reference to its actua1 position, indicate the spacing or movement of the plug in the direction of the axis and away This casing 1 has a cover 8 secured by cap screws or bolts 9. The valve stem 2 extends upwardly from the valve casing 4 through a packing box and gland Ill into the upper or operating mechanism casing I, the two casings being in axial alignment as shown in. Figs. 1 and 3. If so de sired, the lower portion of the packing box in cover 4' may be arranged as to provide for a bearing similar to bearing 3.

The upper end of the valve stem 2 is threaded at l2 or otherwise provided with similar or equivalent lifting mechanism at its upper end and this thread I2 is shown as a multiple thread and in the form of the invention illustrated is a left handed thread which provides for lifting by Fig. 13 is a one-half axial section through from the seat, whereby a clearance is established between the plug and the seat and the terms lowering, dropping or depressing of the plug is used to indicate a motion of the plug in the direction of the axis and toward the seat, whereby thevalve clearance may be closed and the frustoconical surface of the plug is brought in contact with the seat. To avoid reference in the claims to the valve and the motions of the valve in defining the valve gear, the closed position of the valve or any corresponding initial position is referred to as the rearmost position from which the valve and stem are turned forwardly in opening or otherwise operating the valve from closed position, an open position or a position of the gear corresponding to an open position of the valve being referred to as the forward position of the gear, it being understood that various types of valve which are turned or rotated from open to closed position and vice versa in which lifting from the seat is beneficial may be operated by this valve gear. It is conceivable that the gear may be modified to suit valves having more than one open or closed position.

The plug or valve member may be provided with a sealing surface (not shown) similar in form, as the seat or seats of the valve casing. 1

drical and extends through a suitable hole or bearing IS in the cover 8 of the casing 1, being provided inside thecasing and beneath the cover with a flange ll which is secured by means of bolts l8, see Fig. 1, to the carrier I9. In this connection, it should be understood'that in assembling the nut I4 is threaded downwardly over the end of the stem and the cover 8 being removed, the top of the nut is entered into the hole or bearing l6 from below and the cover is then brought downwardly to position. The precise details being subject to wide variation.

The carrier l9, just referredto, is preferably "of U shaped cross section in a vertical plane as direction of a circumference about the valve axis than are lugs 2|. These lugs 2| in all other positions of the carrier l8 rest on or near the bottom wall or floor I of the casing 1 supporting the carrier at the level shown in Fig. 3 in all positions except the open position of the valve, the weight of the carrier being at times carried by follower rollers 24' and 25. The floor of the casing may be referred to as a support or bottom abutment for the carrier, the bottom surface 8 of the top cover 8 being the axially opposite or top abutment. j

The carrier l9 may be further provided with radial arms and hubs 24 and 25 on the ends of which are mounted the cam rollers 24'- and 25' respectively. These rollers engage supporting cam tracks 26 and 21 on the insideof the casing I and may be double and adapted to engage the rollers from above and below, i. e., see Figs. 1 and 3. The upper cam tracks serve to force the plug down on its seat.

The upper and lower U arms 28 of the carrier I9 are slotted at 29, or otherwise adapted for variable connection to the valve stem 2 as hereinafter described. In the form shown, the slots in the two arms are of the same form and location one directly over the other being substan tially parallel to each other, the shape and location of the slots being subject to some variation. The slot, though not exactly radial, is shown as of radial tendency and in the closed position as shown" it is substantially at right angles to the cooperating slot 30 formed in the operating arm 3I which latter is rigidly secured to the valve stem in any suitable manner as by means of set screw 32. This arm is between the carrier arms.

The carrier and arm slots and hence the carrier I9 and the operating arm 3i in which the slots are formed and hence the nut l4 and the valve plug I are connected by an upright control pin 33 shown in top plan in Fig. 1 and in side elevation in Fig. 3. This pin is, in turn, mounted to ride in and is guided by guide and control slots 34 and 34' in the floor 1 and in the bottom surface of the cover 8. The respective slots 34 and 34' being of the same pattern. i. e., parallel and in direct registration in a vertical direction which means in a direction parallel to the valve axis. The slots 34 and 34' are circumferential for the extent of the opening and closing arc of the plug and at the end marked A there is a portion which exactly corresponds to slot 30 in the arm M in the closed position of the valve. Slot 30 in arm 3! and corresponding portion A of slots 34 and 34 are shown substantially straight. If so desired, all or any part of these slots may be slightly curved, for purposes of providing means for causing the plug to rotate during the initial lifting of the plug in opening thereby introducing a spiral motion to the plug.

As already pointed out, the valve plug I when closed fits in its seat in substantial accordance to the usual practice in connection with frustoconical plug valves and as shown the casing 45 is provided with inlet and outlet passages or ports 40, and the plug or valve I has central passage 42 which registers at its ends with the ports 40 in the final open position of the valve.

In the preferred form of the valve, there is a finished seating surface 5', Fig. 6, surrounding each port 40, but the plug surface is shown finishedin the form of a continuous arcuate frustoconical surface.

I The functioning of the valve operating mechanism will now be explained, starting, from the closed position of the valve as shown in Figs. 1 and 3. To operate the valve for purposes of i1- lustration and under ordinary circumstances when the valve is to be hand operated, a handle not shown, may beused, the same being in the form of a plain socket wrench having a cavity to fit the angular head I 5.

end the threads on the valve stem and actuating To conform to established engineering practice, the valve is designed to open with a left' handed, or counterclockwise motion, and to this nut I4 are of a left handed phase.

In opening the valve the nut I4 is rotated counterclockwise and the arm 3| being secured to the valve stem, and the nut I4 being secured in carrier I9, and the pin 33 which connectsthe arm, plug I and the carrier, and hence the nut I4, by its engagement with slots 29 and 30 traveling in the guideways 34 and 34 moves with the rotation of the nut I4 outwardly from its initial position shown in Fig. 1 to the point A of said guideways 34 and 34'. The arm 3| thus remaining stationary while carrier 19 turns through a small arc. The nut I4 is thus caused to rotate relatively to the stem 2 which being integral with the plug I is stationary, i. e., th arm 28 of the carrier with its slots 29 containing pin 33, moving outwardly in Fig. I until the said pin reaches the point A as aforesaid. During this time the'arm 3|, as aforesaid, is stationary and the stem 2 has not rotated, but the nut I4 having turned with the carrier I9 relatively to the stem, raises the latter and the valve or plug in conformance to the pitch of the thread I2, it

being noted that the nut I4 is supported by the carrier I9 which bears by way of lugs 2I on the floor 1' of the casing I. I

By further motion of the nut I4 rotated by any suitable means the pin 33 now moves in counterclockwise rotation but to the right in'Fig. 1 along the circumferential portion B of the guide slots 34 and 34', the carrier I9, nut I4, arm 3|, plug I, and stem 2 and the rollers 24 and 25 rotating together about the valve axis. In the course of this rotation the rollers 24' and 25 arrive on and become supported by the cam tracks 26 and 27.

The pressure on the lugs 2| which rest on the floor at I of the casing I is thus somewhat relieved and as the plug and stem etc., continue to rotate with the nut I4, the carrier I9 and the arm 3| moving together, the lugs 2I enter the cavities 22 in the casing floor 'I' or rather comes over the same and the rollers 24 and 25' pass down to the low part of the earns 25, 21 at C. When the pin 33 reaches the end of the slot 34 at D, the plug reaches its full open position and at the same time drops into its seat in close contact therewith thus preventing the passage of the liquid between the finished frustoconical surface of the plug and the seating surface 5 of the valvecasing .which would cause fouling of the seat. The dropping of the lugs 2! into their respective cavities 22 may also act as stopping means to hold the valve openings and ports in alignment.

Having reference to Fig. 4, the lugs 2| are so placed as to enter cavities 22 in full open position of the valve. Thevalve may be slightly raised when the rollers 24' and 25' encounter the incline of the cams at C, and the incline C eases the valve downwardly preventing the bumping of the valve as lugs 2| pass into the cavities 22.

In closing, which is the next operation to be described, the plug is moved in clockwise rotation 2! which permits the plug, the nut and carrier and arm, as aforesaid, to be moved in right handed rotation as a unit. During this movement the rollers 24' and 25' move up the incline C of the respective cam tracks 26 and 21, the lugs 2| being thusraised out of the cavities 22 and the carrier I! which was dropp d at theend of-the closing operation is thus raised.

By right handed operation, i. e., clockwise swinging of. the operating lever, the pin 33 having, at the end of the opening motion or operation, reached the end of cam slot 34 indicated by D at the right. said pin in the closing operation now moves to the left along said slot to the position A, the arm 3i, carrier I9, nut l4, and the valve stem moving together, it being understood that the plug during this entire closing motion after the rollers 24' and 25' pass up the incline, is elevated so that it clears the seat and moves without friction. stem 2 was taken up by nut H in the initial opening motion and does not change its relation to the nut and carrier until the step of forcing the plug down on its seat in closed position is about to take place; as now to be described.

When the parts move to the position stated in which the pin 33 occupies the position A, the plug is at the closed angle but raised above its seat; and with continued rotation of the nut H in block-- wise direction the arm 3| now being stationary on account of the coincidence of slots 30, 34 and 34' from A to A, the nut and carrier rotate relatively to the arm 3| and stem 2 ina right handed It may be noted here that the direction whereby the thread being left handed,

the stem is moved downwardly through the nut and the plug is forced down against its seat. The nut flange I! treated as part of the carrier reacts against the bottom surface 8 of the cover 8 of the casing which acts as an upper abutment. It will be understood that at this time the followers 24', 25' having long since left the cams 26 and 21 and the lugs 2| having been raised from cavities 22 have rested on and moved along the floor I of the casing I. The parts are then returned to the position shown in Figs. 1 and 3.

An important accomplishment of the invention, as illustrated in Figs. 1 to 9, resides in the practically frictionless opening and closing of large valves controlling high pressures and particul-- larly in the combination in automatic relation of the lifting and opening operation and the return of the plug to its seat in open position without variation of the normal actuating motion of the lever or other equivalent means employed. The

raising of the plug from full open position by the rotation of the valve by the lever in closing direction and the mechanism whereby it is returned to closed position and the means and manner of forcing the plug down against its seat, both said has been previously devised for this purpose.

Figs. 10, 11, 12, 13 and 14 show an improved form of plug valve adapted for use with the regular type of operating mechanism or with the improved lifting type of operating mechanism just described. This improved plug valve has a casmg to with a frustoconical seat 5| and opposite aligned ports or passages 52, 52' leading through the casing to valve seat 5|.

As already pointed'out, it has been demonstrated and is a well known fact that in, theinitial opening of plug valves, particularly the plug valves of large size operated under heavy hydraulic pressures excess resistance is encountered. This resistance is understood to be due to a jet of liquid from the initial opening of the valve impinging on the inclined opposite side of the deflected passage or hole in the plug. The jet is directed at an angle to the normal flow through the valve and thus caused to strike the adjacent end of the wall of the plug opening or passage tending to close the valve or resist opening.

This difliculty has been overcome in the new form of valve by the provision of a central stationary core, the plug proper being in the form of a sleeve. This stationary core, as hereinafter pointed out, has a passage in full alignment with the Ports in the seat so that in opening the impingement of the initial jet strikes the wall of the passage in the rigidly supported stationary core and ha no appreciable effect in the way of resistance opposed to the opening of the valve.

The stationary core referred to is indicated by reference character. 53, being, in the form of the invention shown, of substantially cylindrical outline with the axis of the cylinder coinciding with the valve axis, this core is provided with a. central valve passage or port 54 in precise alignment with the ports 52 and 52'. secured to the base of the valve casing in any suitable manner as by pins 55 and screw 56. The cylindrical form of the core not only facilitates turning of the valve proper relatively to the core, as hereinafter described, by fitting in a similar opening therein but makes it possible to insert the valve member or sleeve valve 51 from above whereby it enters between the seat and the outer wall of the stationary core 53.

The valve member 51 which may be referred to as a sleeve plug valve is shown in the form of an externally frustoconical sleeve or hollow plug having a cylindrical opening 58 finished to fit the outer surface of the core 53 and to permit turning of the sleeve relatively to the core.

The valve or. sleeve plug 51 is shown as provided with ports 59 which are aligned and normally adapted to register with the seat ports 52 and 52' in the open position of the-valve and likewise to register with the ends of the core passage 54, the core andpassage, as already pointed out, being stationary. The arrangement, of the ports may be varied to suit the practice or installation, the elimination of resistance to opening as herein outlined being the main object of the-invention.

In the form of the invention shown, the core 53 is somewhat shorter than the plug and its top fiat surface 60 is below the upper arc SI of the ports 52 and 52'. The passage 54 through the core being open at the top into the sleeve plug 51, as indicated, is, therefore, less then full cylindrical but is regarded as sufiiclent to avoid the harmful closing tendency already described and it has the advantage that the arrangement provides for top wall 82 in the sleeve plug and the connection thereto of the valve stem 63.

Figs. 11 and 12 show the casing support or struts 6 extending to the upper operating casing I. The operation and advantages of the new type of valve and valve operating mechanism and the construction thereof having been fully described, I would have it understood that the specific terms In the form shown, it is to raise the stem relatively to the carrier, and

herein are used descriptively rather than a limiting-sense, the scope of the invention being defined in the claims.

What I claim as new and desire to secure by Letters Patent is:

1. An operating mechanism for a valve of the rotary type having a casing and a stem, said operating mechanism comprising a nut threaded on the stem, a carrier secured to the nut, abutment means limiting the play of the nut in axial directions, whereby the nut is enabled to move the stem in an axial direction as it is rotated relatively thereto, an operating arm connected to the stem to turn the same, means connecting the carrier to the arm, said connection having a control, the connection and control comprising means causing the arm and carrier and stem to move in correspondence withthe nut, turning together forwardly and backwardly about the axis of the stem through a predetermined are, said means including a provision for permitting forward turning of the nut prior to the forward turning of the arm and stem, and means for lowering the carrier and nut at the end of said for-ward turning motion of the stem, whereby the stem is raised at the beginning of said forward motion and lowered at the end of said motion.

2. An operating'mechanism for a rotary valve having a casing and a stem, said operating mechanism comprising a nut threaded on the stem, a carrier secured to the nut, abutment means limiting the play of the carrier in axial directions, an operating arm connected to the stem to turn the same, means connecting the carrier to the arm, said connection having a .control in the form of co-operating guides, said connection and control comprising means causing the arm and carrier and hence the stem to turn in correspondence with the nut about the axis of the stem, moving together forwardly and backwardly through a predetermined are but including a provision for permitting turning of the nut prior to the turning of the arm to raise the stem prior to the forward turning motion of the stem and to lower the stem at the end of the arcuate motion of the stem in the backward direction and means for lowering the carrier and hence the stem at the end of the forward turning motion and means for raising said carrier and thereby raising the stem at the beginning of the backward turning motion.

3. An operating mechanism for a rotary valve having a casing and a stem, said operating mechanism comprising nut threaded on the stem, a carrier secured to the nut, abutment means limiting the play of the carrier in axial directions, an' operating arm connected to the stem to turn the same, means connecting the carrier to the arm, said latter connections having controlling means, said connections and control including means causing the carrier and stem to move in correspondence with the nut to turn about the axis of the stem moving together forwardly and backwardly through an are, said means including a provision for permitting turning of the carrier and nut prior to the turning of the arm and stem in the forward turning motion and at the end of the turning motion of the stem in the backward turning through said are, means for lowering the carrier, the nut, and the stem near the end of the forward turning motion and means for raising said carrier, nut and stem at the beginning of the backward turning motion, the said turning of the carrier and the nut relatively to the arm prior to the forward rotation serving the opposite turning of the same relative to the stem at the end of the backward turning motion v serving to lower the stem to initial position, the

lowering of the carrier and nut and stem at the end of the forward turning serving to bring the stem to its initial level and the raising of the carrier and nut at the beginning of the backward turning motion serving to return the carrier and nut to their initial elevation.

4. An operating mechanism for a rotary valve having a casing and a stem, said operating mechanism comprising a nut having a threaded en-' gagement with the stem, a carrier connected to the nut to turn therewith, an actuating arm operatively connected to said stem for turning said stem forwardly and backwardly through a pre-- determined are said arm and said carrier having slots which cross in the backward position of the arm and the corresponding position of the stem, a travelling control pin extending through said slots in approximate parallelism with said stem, said casing having a guiding slot in a stationary portion of the casing also engaged by the pin, said guiding slot having a portion which in the closed position of the valve extends outwardly in substantial parallelism and in registration with the slot in said actuating arm, said guiding slot also having a circumferential portion extending from said parallel portion of said guiding slot and in said forward direction therefrom, through an arc corresponding to the length of said predetermined arc, said pin maintaining different portions of said slots in registration in the different positions of the operating mechanism and stem.

5. An operating mechanism for a rotary valve having a casing and a stem, said operating mech anism comprising a nut; threaded on said stem, 2. carrier operatively connected to the nut to turn the same, an actuating anm operatively connected to the steni to rotate the stem forwardly and backwardly through an arc, said arm and said carrier having slots which cross in the rearmost position of the parts, a control pin extending approximately in the direction of the axis of the stem through said slots, the casing having a guiding slot in a stationary portion thereof, said latter slot also being engaged by the pin, said guiding slot having a portion which extends outwardly and in registration with the slot in said actuating arm in the rearmost position of the parts, said guiding slot having a circumferential portion extending from said outwardly extending portion of said slot in a forward direction, means providing for the lowering of the carrier and stem as the parts approach the forward position and follower means on the carrier and means on the casing co-operating therewith to raise the carrier as it is rotated from forward to rearmost position.

6. An operating mechanism for a rotary valve having a casing and a threaded stem, said operating mechanism comprising a carrier mounted to rotate forwardly and backwardly through a predetermined arc, a nut engaging the thread and secured to said carrier to rotate therewith, an

arm connected to the stem to turn the same, means supporting the carrier in axial directions,

means connecting said arm to said carrier and control means for said connection providing for the rotation through a small arc of the nut relatively to the arm and stem prior to forward rotation of the stem whereby the stem is lifted causing the same to be supported on said carrier. said means-rpei mitting downward motion of the carrier at the end of said forward turning motion, and other means for raising the carrier and stem 'in the initial portion of the backward motion,

said connecting permitting rotation of the carrier and nut relatively to the arm and stem at the end of the backward motion to initial position,

said rotation being the reverse of the initial rotation of the nut relatively to the stem and serving to move the stem downwardly relatively to the carrier and casirm said supporting means for the carrier comprising an upper abutment against which the nut reacts for this purpose. r

7. -An operating mechanism for a rotary valve having a casing and stem the same comprising an operating nut having a threaded engagement with the stem, a carrier connected to the nut to turn therewith forwardly and backwardly through a predetermined arc, an arm connected to the stem to turn the same and having control means whereby it is connected to the carrier to operate in correspondence with the carrier providing for initial turning o! the nut relatively to the stem tolift the stem at the beginning of the forand lowering the stem, a carrier connected to said ward tuming and to lower it at the end of the backward turning motion, means for lowering the stemand nut and carrier at the end 01. the forward turning motion and means for raising the stem and nut and carrier at the beginning of the backward turning motion.

8. An operating mechanism for a rotary valve having a casing and stem, the same comprising an actuating member having means for lifting member to turn therewith forwardly and backwardly through a predetermined arc, an arm connected to the stem to turn the same and having control means wherebyjt is connected. to the carrier to turn in correspondence with the carrier and to said member to lift the stem at the beginning of the forward turning motion and to lower it at the end 0! the backward turning motion, and means for lowering the carrier and stem at the end of the forward turning motion and for raising the carrier and stem at the beginning of the backward turning motion.

ROBERT BISCHOFF. 

